Low permeability fabric

ABSTRACT

A fabric comprising a plurality of coiled yarns arranged in side-by-side intermeshing relationship and having elongated pintles extending through intermeshed portions of the yarn. Elongated stuffer elements extend through central portion of each of the coils in between adjacent pintles. The stuffer elements respond to a given input after insertion to expand and fill the central portions of each of the coils. The input may be temperature, light, sound, chemical and tension. In one form, the stuffer elements formed from auxetic material which is placed in tension, after insertion, to cause the stuffer elements to expand and reduce the permeability of the fabric.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to spiral fabrics, and, more particularly, to such fabrics having stuffers inserted into open areas to reduce the permeability of the fabric.

2. Description of the Related Art

Spiral fabrics wound with coiled filaments are used in such applications as dryers, PMC, and other applications. They are typically assembled using a series of right and left handed monofilament coils. Adjacent coils are connected by pintles, typically formed from a monofilament. The permeability of the assembled fabric may be reduced by insertion of stuffer yarns into the openings formed between adjacent pintles. The stuffers may be extruded or braided and come in a variety of elongated solid geometric shapes. The stuffers may be effectively locked into the fabric structure by heat setting the monofilament or by applying a polymeric resin material at each edge of the fabric. An encapsulated composite of spiral loops, stuffers and resin results. Due to the nature of the manufacturing process, it becomes progressively more difficult to achieve reductions in permeability for wider fabrics approaching 9 meters wide because of the difficulty of inserting the stuffers in the open spaces in the woven fabric.

When significantly lower permeability is required, it is difficult to seal all the space in the fabric because the geometric shapes placed in the fabric fail to intimately conform to the intricate shape of the coiled filaments.

What is needed in the art is a fabric of the above type that has a significantly lower permeability and which is made using a simplified process.

SUMMARY OF THE INVENTION

The invention, in one form, is directed to a fabric having a plurality of coiled monofilaments arranged in side-by-side, intermeshing relationship and elongated pintles extending through intermeshed portions of the coiled monofilaments. Elongated stuffer elements extend through central portions of each of the coils in between adjacent pintles. The stuffer elements respond to a given input after insertion to expand and fill the central portion of each of the coils.

The invention, in another form, is directed to a method of forming a fabric having the steps of arranging a plurality of coiled monofilaments in side-by-side intermeshing relationships. Pintles are extended through intermeshed portions of the coiled monofilaments and tubular stuffer elements are extended through central portions of the monofilaments in between the pintles. The tubular stuffer elements are responsive to a given input to expand and fill the central portion of each of the coils and after the stuffer elements are in place they are subjected to the given input.

In yet another form the invention involves a fabric having a plurality of coiled monofilaments in side-by-side intermeshing relationship. Pintles extend through intermeshed portions of the coiled monofilaments between adjacent pintles and tubular stuffer elements extend through central portions of the coiled monofilaments. The stuffer elements are formed from auxetic material to expand in response to tension and fill the central portion of each of the coils.

An advantage of the present invention is the easy insertion of stuffer elements with substantial reductions in permeability.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic side view of a fabric including stuffer elements embodying the present invention; and

FIG. 2 is a plan view of a fabric with stuffer elements also embodying a form of the present invention.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly to FIG. 1, there is shown a plurality of stuffer elements 10 in place in a fabric made of a plurality of coiled yarns 14 intermeshing to form continuous coiled or spiral loops in the MD (machine direction). At the intersections 16 of the coiled yarns there are a series of pintles 18 which extend in a CMD (cross machine direction). The fabric 12 is formed to provide a belt and the elongated portion of the belt is in the MD while the CMD extends at right angles to the plane of FIG. 1. Although the yarns have been described as coiled, an alternative term for designating their shape and interaction is spiral. The yarns may be formed from a variety of materials suitable for use as a dryer fabric. One type of material suitable for this purposes is polyester. It should be apparent, however, that other materials may be employed for the yarns with equal results.

After the spiral monofilament, spiral yarns or coiled yarns 14 are interweaved and the pintles 18 are inserted, tubular stuffers are inserted in a CMD fashion. The tubular stuffers 10 are sized to be received in the open spaces between adjacent pintles 18. The stuffer elements 10 are fashioned from material having a property that is responsive to an external input, shown schematically by reference character 20, which causes the stuffer elements to expand and substantially fill the spaces between pintles, as shown by stuffer element 10 a to the right of FIG. 1.

The external input is selected from one of heat, temperature, light, sound, chemical and tension to cause the stuffer elements to expand in place. The materials may be responsive to the external input to expand in substantially an irreversible condition or remain in the expanded state so long as the input is present.

The advantage of the materials set forth above is that they can be sized to easily fit into the spaces in the coiled fabric between pintles 18 but, in place, subjected to the external input from element 20 to expand them to substantially completely fill the spaces in the fabrics. This enables permeability levels significantly lower than those experienced in prior art coiled or spiral fabrics.

FIG. 2 shows yet another example of a material that is subjected to an external input to expand, once it is in place and fill the spaces between the pintles 18. In this case, the material is selected from a type of material known as auxetic material. This material exhibits a negative Poisson's ratio. Unlike an elastic band for example, which becomes thinner when stretched, an auxetic material will become thicker. Conversely, when auxetic material is compressed, it will become thinner. Thus, when stuffer element 10 is made from auxetic material, and it is pushed into the spaces between the pintles 18, it becomes thinner. Once the stuffer element 10 is in place, its ends 22 and 24 are stretched thus causing the thickness of the stuffer element 10 to increase. The ends 22 and 24 are held in tension by securing them to the ends 26 and 28 of the fabric 12. Thus the auxetic material is held in the expanded position during operation of the fabric 12.

While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims. 

1. A fabric comprising: a plurality of coiled monofilaments arranged in side-by-side, intermeshing relationship and elongated pintles extending through intermeshed portions of said coiled monofilaments; and elongated stuffer elements extending through central portions of each of said coils in between adjacent pintles, said stuffer elements responding to a given input after insertion to expand and fill the central portions of each of said coils.
 2. A fabric as claimed in claim 1, wherein said stuffer elements are responsive to a temperature input to expand in place.
 3. A fabric as claimed in claim 1, wherein said stuffer elements are responsive to a light input to expand in place.
 4. A fabric as claimed in claim 1, wherein said stuffer elements are responsive to a sound input to expand in place.
 5. A fabric as claimed in claim 1, wherein said stuffer elements are responsive to chemical input to expand in place.
 6. A fabric as claimed in claim 1, wherein said stuffer elements are responsive to applied tension to expand in place.
 7. A fabric as claimed in claim 6, wherein said stuffer elements are formed from auxetic material.
 8. A method of forming a fabric comprising the steps of: arranging a plurality of coiled monofilaments in side-by-side intermeshing relationships; extending pintles through intermeshed portions of said coiled monofilaments; extending tubular stuffer elements through central portions of said monofilaments in between said pintles, said tubular stuffer elements being responsive to a given input to expand and fill the central portion of each of said coils; and after said stuffer elements are in place, subjecting them to said given input.
 9. A method of forming a fabric as claimed in claim 8, wherein said stuffer elements are responsive to temperature input to expand and after said stuffer elements are in place said stuffer elements are subjected to a temperature input.
 10. A method as claimed in claim 8, wherein said stuffer elements are responsive to a light input to expand and after said stuffer elements are in place said elements are subjected to a sound input.
 11. A method as claimed in claim 8, wherein said stuffer elements are responsive to a chemical input to expand and said chemical input is applied to said stuffer elements after they are in place.
 12. A method as claimed in claim 8, wherein said stuffer elements are responsive to tension to expand and said stuffer elements are subjected to tension after they are in place.
 13. A method as claimed in claim 12, wherein said stuffer elements are auxetic.
 14. A method as claimed in claim 13, wherein said stuffer elements are pressed into place in between said pintles thereby reducing their thickness for insertion.
 15. A method as claimed in claim 13, wherein said stuffer elements are kept in tension by securing them to outer edges of said fabric. 